Poor oral hygiene is the main cause of most cases of halitosis (bad breath), but bad breath can also indicate other medical conditions. According to a study in the journal Gut in April 2015, the latest breath testing technology can detect gastric cancer in its early stages.
However, stomach cancer is not the only thing that can cause odor on your breath.
Health conditions that cause bad breath
Gum disease
Gum disease can cause bad breath. Studies in 2012 found a direct link between periodontitis and gingivitis (gingivitis) with bad breath. This halitosis is the result of bacteria living in the patient's mouth.